We will continue to evaluate the role of steroid profile and thyroid hormone profile monitoring in optimizing both diagnosis and treatment of different endocrine diseases.We will also examine the role of our new free steroid profile and free 25 OH Vitamin D3 assays in health and disease. The work described above has been published in numerous papers, a few of which are listed below. Soldin SJ, Soldin OP. Steroid Hormone Analysis by Tandem Mass Spectrometry. Clin Chem. 2009;55:1061-6. Soldin SJ, Cheng LL, Lam LY, Werner A, Le AD, Soldin OP.Comparison of FT4 with log TSH on the Abbott Architect ci8200: Pediatric reference intervals for free thyroxine and thyroid-stimulating hormone.Clin Chim Acta. 2010;411: 250-2. Jonklaas J, Kahric-Janicic N, Soldin OP, Soldin SJ. Correlations of Free Thyroid Hormones Measured by Tandem Mass Spectrometry and Immunoassay with Thyroid-Stimulating Hormone Across 4 Patient Populations. Clin Chem. 2009;55:1380-88. Soldin OP, Soldin SJ. Thyroid hormone testing by tandem mass spectrometry. Clin Biochem. 2011;44:89-94 Van Deventer HE, Mendu DR, Remaley AT, Soldin SJ. Inverse Log-Linear Relationship between Thyroid-Stimulating Hormone and Free Thyroxine Measured by Direct Analogue Immunoassay and Tandem Mass Spectrometry. Clin Chem 2011 Jan;57(1):122-7. Jonklaas J, Holst JP, Verbalis JG, Pehlivanova M, Soldin SJ. Changes in steroid concentrations with the timing of corticotropin stimulation testing in participants with adrenal insufficiency.Endocr Pract. 2012 Jan-Feb;18(1):66-75. Gounden V, El-Maouche D, Stolze BR, Muniyappa R, Soldin SJ.LC-MS/MS detection of increased Androstenedione levels in patients receiving Danazol therapy.Ther Drug Monit. 2014 May 9. Van Deventer HE, Soldin SJ. The expanding role of tandem mass spectrometry in optimizing diagnosis and treatment of thyroid disease.. Advances in Clinical Chemistry 2013:61;127-152. Gounden V,Jonklaas J, Soldin SJ. A Pilot Study: Subclinical Hypothyroidism and Free Thyroid Hormone Measurement by Immunoassay and Mass Spectrometry. Clinica Chimica Acta 430 (2014) 121124. Stolze BR,Gounden V,Gu J,Merke DP,Skarulis MC,Soldin SJ. An improved micro method for the measurement of steroid profiles by tandem HPLC MSMS andits use in assessing diurnal effects on steroids studied.Submitted to Clin Chem. Gounden V, Soldin SJ. Tacrolimus Measurement: Building a Better Immunoassay. Clin Chem. 2014 Apr;60(4):575-6. Gounden V,Soldin SJ. Clinical Use of Reference Intervals Derived from Some CALIPER Studies Questioned. Clinical Chemistry 2014:60;416-7. Jonklaas J, Sathasivam A, Wang H, Finigan D, Soldin OP, Burman KD, Soldin SJ.3,3'-diiodothyronine concentrations in hospitalized or thyroidectomized patients: results from a pilot study.Endocr Pract. 2014 Aug 1;20(8):797-807 Jonklaas J, Sathasivam A, Wang H, Gu J, Burman KD, Soldin SJ.Total and free thyroxine and triiodothyronine: Measurement discrepancies, particularly in inpatients.Clin Biochem. 2014 Sep;47(13-14):1272-8. Debono M, Mallappa A, Gounden V, Nella AA, Harrison RF, Crutchfield CA, Backlund PS, Soldin SJ, Ross RJ, Merke DP.Hormonal Circadian Rhythms in Patients with Congenital Adrenal Hyperplasia: Identifying Optimal Monitoring Times and Novel Disease Biomarkers.Eur J Endocrinol. 2015 Sep 4. pii: EJE-15-0064